Communication equipment with boundary scan elements

ABSTRACT

A communication system includes a plurality of boundary scan elements including input and output terminals and a plurality of boundary cells individually assigned to the respective input terminals and output terminals, a plurality of data output units connected parallel to the boundary scan elements, and a communication controller connected to the boundary scan elements in series. The communication controller transmits and receives through the boundary scan elements control data for individually controlling the data output units. A signal data communication line is connected with the data output units in parallel, and a signal processing unit is connected with the signal data communication line and the communication controller for transmitting output data from the data output units under a control of the communication controller.

TECHNICAL FIELD

The present invention relates to a communication system for controllingterminal units through boundary scan elements, and particularly to acommunication system which can quickly transmit output data from theterminal units.

BACKGROUND OF THE INVENTION

A boundary scan test method has been proposed as one of the inspectionmethods with a plurality of IC chips arranged over a printed wire boardwith printed wiring formed thereon, to see whether or not connectionbetween each IC chip and each printed wiring is properly made andwhether or not each printed wiring is not broken.

This boundary scan test method can be applied to integrated circuits (ICchips) into which boundary scan elements are incorporated. The boundaryscan element, for example as shown in FIG. 4, includes a plurality ofboundary cells 114 individually provided between input/output terminalsof an internal logic 111 for implementing the inherent functions of theintegrated circuit 110 and input/output terminals 112/113 of theintegrated circuit 110, a TAP controller (TAP circuit) 119 forcontrolling input and output of data to or from the boundary cells 114,a TDI terminal 120 for receiving test data, a TDO terminal 121 fortransmitting test data, a TCK terminal 122 into which a clock signal isinput, and a TMS terminal 123 for receiving a mode signal for switchingthe operation mode of the TAP controller 119; and, if required, it isfurther provided with a bypass register 115, an ID CODE register 116, aninstruction register 117, a TRS terminal 124 for receiving a resetsignal, or the like. In this connection, the bypass register 115 toinstruction register 117 is referred to as boundary scan register (118).

To describe the respective terminals or the signals to be input/outputthrough the respective terminals in detail, TDI (Test Data In) is asignal for serial-inputting instructions and data to a test logic, andis sampled at rising edges of TCK. TDO (Test Data Out) is a signal forserial-outputting data from the test logic, the output value beingchanged at falling edges of TCK. TCK (Test Clock) supplies a clock tothe test logic. It is a dedicated input for enabling the use of a serialtest data path independent of the system clock inherent to thecomponent. TMS (Test Mode Select) is a signal for controlling the testoperation, and is sampled at rising edges of TCK. The TAP controllerdecodes this signal. TRST (Test Reset) is a negative logic symbol for asynchronously initializing the TAP controller, and is optional.

The integrated circuit 110 into which such boundary scan element isincorporated can be tested on the operating state thereof and theconnecting relationship between this integrated circuit 110 and externaldevices, by the procedures described below.

First, in checking the quality of the internal logic 111 of theintegrated circuit 110, serial data (test data) are input to the TDIterminal 120 of the integrated circuit 110 as they are shifted, andthereby the test data are set into the respective boundary cells 114corresponding to the respective input terminals 112. In this state, theintegrated circuit 110 is operated before the data set in the respectiveboundary cells 114 corresponding to the respective output terminals 113are shifted for output from the TDO terminal 121, and, on the basis ofthe corresponding relationship between the serial data (test resultdata) thus obtained and the test data input to this integrated circuit110, the internal logic 111 of the integrated circuit 110 is tested forits quality.

The boundary scan test method can also be carried out on a plurality ofintegrated circuits as long as the boundary scan elements areincorporated therein.

For example, a plurality of integrated circuits 110 mounted on asubstrate 126 as shown in FIG. 5 can also be subjected to a test forbreakage and the like of the printed patterns between the integratedcircuits 110, along with a test on the integrated circuits 110themselves.

In this case, the respective boundary scan elements incorporated in theplurality of integrated circuits 110 are connected in series with eachother. Specifically, the TDO terminal 121 of the first integratedcircuit 110 (the left in the drawing) and the TDI terminal 120 of thesecond integrated circuit 110 (the right in the drawing) are connectedwith each other, the output terminal 129 of a boundary scan controllerboard 128 provided in host computer unit 127 or the like and the TDIterminal 120 of the first integrated circuit 110 are connected with eachother, and the input terminal 130 of the boundary scan controller board128 and the TDO terminal 121 of the second integrated circuit 110 areconnected with each other. The test procedures are as follows:

In testing breakage, short circuit, and the like of the printedpatterns, a test data preparing tool 131 or the like is used to preparetest data (serial data), which is output from the output terminal 129 ofthe boundary scan controller board 128 and is input to the TDI terminal120 of the first integrated circuit 110 while shifted, setting the testdata into the respective boundary cells 114 corresponding to therespective output terminals 113 in this integrated circuit 110. In thisstate, the data stored in these respective boundary cells 114 are outputfrom the respective output terminals 113 provided in the firstintegrated circuit 110 as shown in FIG. 6, and are input through therespective printed patterns 133 constituting a system bus and the liketo the respective input terminals 112 of the second integrated circuit110, and further fetched into the respective boundary cells 114corresponding to these respective input terminals 112.

Thereafter, the data stored in the respective boundary cells 114 ofthese respective integrated circuits 110 are shifted and fetched throughthe input terminal 130 of the boundary scan controller board 128 as theyare analyzed by using a test result analyzing tool 132 or the like, sothat a test can be made for breakage, short circuit, and the like insuch a test range 135 as the printed patterns 133 providing connectionbetween the integrated circuits 110.

Next, in inspecting the internal logic 111 of the respective integratedcircuits 110, test data are output from the output terminal 129 of theboundary scan controller board 128, and are input to the TDI terminal120 of the first integrated circuit 110 as they are shifted, so as to beset into the respective boundary cells 114 corresponding to therespective input terminals 112 of this integrated circuit 110 as shownin FIG. 8.

Subsequently, this integrated circuit 110 is operated, and the resultingdata are fetched into the respective boundary cells 114 corresponding tothe respective output terminals 113 before the data stored in theserespective boundary cells 114 are shifted to be output from the TDOterminal 121 of the first integrated circuit 110. Here, the secondintegrated circuit 110 is brought into a bypass state as shown in FIG. 7by the boundary scan controller board 128, so that the data output fromthe TDO terminal 121 are bypassed through the second integrated circuit110 and fetched through the input terminal 130 of the boundary scancontroller board 128. Then, the test analyzing tool 132 or the like canbe used for analysis of the fetched data to test whether or not thefirst integrated circuit 110 operates properly.

Next, in the cases of inspecting the second integrated circuit 110, theboundary scan controller board 128 similarly brings the first integratedcircuit 110 into a bypass state as shown in FIG. 7 before test data areoutput from the output terminal 129 of the boundary scan controllerboard 128 and bypassed through the first integrated circuit 110. Then,the test data are input to the TDI terminal 120 of the second integratedcircuit 110 while shifted, to be set into the respective boundary cells114 corresponding to the respective input terminals 112 of thisintegrated circuit 110 as shown in FIG. 8. Subsequently, this integratedcircuit 110 is operated, and the resulting data are fetched into therespective boundary cells 114 corresponding to the respective outputterminals 113. Thereafter, the data stored in the respective boundarycells 114 are shifted to be output from the TDO terminal 121, andfurther fetched through the input terminal 130 of the boundary scancontroller board 128. Then, the fetched data can be analyzed by usingthe test result analyzing tool 132 and the like, so as to test whetheror not the second integrated circuit 110 operates properly.

In this way, a substrate 126, as long as using integrated circuits 110into which boundary scanning circuits are incorporated, can be testedfor the quality of the respective integrated circuits 110 themselves andthe connecting relationship between the integrated circuits 110 and thelike by conducting the boundary scan test method.

Now, it was found by the present inventor that when integrated circuitsinto which such boundary scan elements are incorporated are used toconstitute the substrate or the like of a sensor module, input andoutput of serial data can be made to or from the respective integratedcircuits mounted on the substrate 126 at a rate on the order of 20 Mbpswithout the use of communication integrated circuits or the like.

Then, a communication system was proposed which applies the boundaryscan elements to carry out communication with host computer units andthe like without the use of communication devices.

FIG. 9 is a block diagram showing an example of the communication systemto which the boundary scan elements are applied.

The communication system 140 shown in this figure includes: acommunication controller device 141 for carrying out the transmitting ofcontrol data, the collection of detected data, and the like; a pluralityof sensor units 142 a-142 c for carrying out the monitoring of an objectto be monitored; a plurality of boundary scan elements 143 a-143 cprovided for each of these sensor units 142 a-142 c, the boundary scanelements carrying out such processing as fetching the control dataoutput from the aforesaid communication controller device 141 to supplythe same to the respective sensor units 142 a-142 c, and fetching thedetected data or the like output from these respective sensor units 142a-142 c to supply the same to the aforesaid communication controllerdevice 141; and communication lines 144 for providing connection betweeneach of these boundary scan elements 143 a-143 c and the aforesaidcommunication controller device 141. The boundary scan elements areconnected in series to the communication controller device 141.Specifically, the connection is made in such a manner that the outputterminal 141 a of the communication controller device 141 is connectedto the TDI terminal of the boundary scan element 143 a, the TDO terminalof the boundary scan element 143 a connected to the TDI terminal of thenext boundary scan element 143 b, and so on, and the TDO terminal of theboundary scan element 143 c is connected to the input terminal 141 b ofthe communication controller device 141.

The function of this communication system 140 is as follows:

The respective boundary scan elements 143 a-143 c function insynchronization with the clock signal transmitted from the TCK terminal141 d of the communication controller device 141, and the operation modeof each TAP controller is switched by the TMS signal transmitted fromthe TMS terminal 141 c of the communication controller device 141.

Now, in driving the respective sensor units 142 a-142 c according to theinstruction from the host computer unit 145, control data (serial data)are output from the output terminal 141 a of the communicationcontroller device 141, and they are supplied to the respective boundaryscan elements 143 a-143 c and set into the boundary cells correspondingto the output terminals. Then, the control data set are output from theoutput terminals, and supplied to the respective sensor units 142 a-142c corresponding to the respective boundary scan elements 143 a-143 c,thereby driving these units.

Moreover, in the cases of collecting the detected data from therespective sensor units 142 a-142 c according to the instruction fromthe host computer unit 145, the detected data of the respective sensorunits 142 a-142 c are once set in the respective boundary cellscorresponding to the input terminals of the corresponding, respectiveboundary scan elements 143 a-143 c. Then, they are output as serial datafrom the TDO terminals, and fetched through the input terminal 141 b ofthe communication controller device 141.

Such communication system 140, when setting control data into therespective boundary scan elements 143 a-143 c or when outputting thedetected data from the respective boundary scan elements 143 a-143 c,can be maximized to 20 Mbps in data transfer rate, thereby allowing thetransfer of communication data at higher rates than those ofconventional communication systems.

However, the communication system described above had a problem in thatwhen the detected data of the terminal units such as sensor unitsconnected to the boundary scan elements are enormous, e.g. picturesignals and the like, a drop in the transfer rate is undeniable and theeffect of the high-rate data transfer obtained by the application of theboundary scan elements as communication elements is not exertedsufficiently.

Moreover, since the boundary scan elements can only input and outputinformation in the form of digital signals, there was a problem in thatthey cannot fetch information in an analog signal form.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a communication systemwhich can transfer data from terminal units at higher rates.

Another object of the present invention is to provide a communicationsystem which can transfer analog signals from terminal units at higherrates.

According to the present invention, there is provided a communicationsystem comprising: a plurality of boundary scan elements including aplurality of boundary cells individually assigned to respective inputterminals and output terminals, a TAP circuit for controlling input andoutput of data to or from the aforesaid boundary cells, a TDI terminalfor inputting serial data to be supplied to the aforesaid boundarycells, a TDO terminal for outputting data from the aforesaid boundarycells in the form of serial data, a TCK terminal into which a clocksignal is input, and a TMS terminal into which a mode signal forswitching the operation mode of the aforesaid TAP circuit is input; aplurality of terminal units each connected with each of the aforesaidboundary scan elements or provided with an IC into which each of theelements is incorporated; and a communication controller connected withthe aforesaid boundary scan elements in series fortransmitting/receiving through the aforesaid boundary scan elementscontrol data for individually controlling the aforesaid terminal units,wherein the aforesaid terminal units are connected in parallel and asingle data communication line for transmitting output data of theaforesaid terminal units to the aforesaid communication controller isprovided.

In the present invention, the communication controller controls theterminal units by transmitting control data thereto through the boundaryscan elements. Then, data obtained by the terminal units are directlytransmitted to the communication controller through the datacommunication line without the intermediary of the boundary scanelements.

This enables the high-rate transfer of data even when the output data ofthe terminal units are enormous, and allows the transfer of the outputdata even when they are analog signals.

Moreover, the output data are transmitted through a single datacommunication line, so that wiring of the system is simplified. Inaddition, the boundary scan elements are driven synchronously, so thatwhen the respective terminal units are switched to transmit their outputdata through the data communication line, little time rag is producedbetween the output data and interference therebetween is avoided.

In the present invention, the terminal units include various sensorunits, such as monitoring camera units, and the output data include thedetected data of the sensor units, such as moving picture signals andstill picture signals.

The control data include not only the data to be transmitted to theterminal units for the control of the terminal units, but also thestatus data and the like of the terminal units to be transmitted backfrom the terminal units.

The boundary scan elements include not only independent, separatepackages but also those incorporated in other ICs. Besides, the inputterminals and output terminals represent, in the case where each of theboundary scan elements is an independent package, the input terminalsand output terminals thereof, and represent, in the case where theboundary scan elements are incorporated into other ICs, the inputterminals and output terminals of the ICs. Then, the aforesaid outputterminals and the aforesaid input terminals are connected to the inputterminals and the output terminals of the terminal units, respectively,so that the data of the boundary cells are output to the terminal unitsand data are conversely input to the boundary cells.

Moreover, according to the present invention, the communication systemdescribed above may be provided in which: the output data are analogsignals; and an analog signal processor for processing the output datamay be provided between the communication controller and thecommunication liner. In this invention, the provision of the aforesaidanalog signal processor can ease the load on the communicationcontroller to quickly perform the processing of analog signals.

Furthermore, according to the present invention, there is provided theabove-described communication system in which: the boundary cellsinclude a plurality of input-terminal-side boundary cells connected inseries and assigned to the respective input terminals individually, anda plurality of output-terminal-side boundary cells connected in seriesand assigned to the respective output terminals individually; and theinput-terminal-side boundary cells and the aforesaidoutput-terminal-side boundary cells are connected in parallel betweenthe TDI terminal and the TDO terminal.

In this invention, the boundary cells are not coupled all in series asconventionally, but are divided into the input-terminal-side boundarycells assigned to the input terminals and the output-terminal-sideboundary cells assigned to the output terminals, which are connected inparallel between the TDI terminal and the TDO terminal. Accordingly, forexample, when data from the TDI terminal are being set into theoutput-side boundary cells, direct transfer of the data to theoutput-side boundary cells can be made without the intermediary of theaforesaid input-terminal-side boundary cells, which can further realizethe higher-rate transfer of data between the boundary scan elements andthe communication controller or the terminal units.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a first embodiment of thecommunication system of the present invention;

FIG. 2 is a block diagram showing a second embodiment of thecommunication system of the present invention;

FIG. 3 is a block diagram of the boundary scan element 11 a-11 c in FIG.2;

FIG. 4 is a block diagram of a conventional boundary scan element;

FIG. 5 is a block diagram showing an example of a boundary scan testusing the boundary scan elements shown in FIG. 4;

FIG. 6 is a schematic diagram showing an example of a boundary scan testusing the boundary scan elements shown in FIG. 4;

FIG. 7 is a schematic diagram showing an example of a boundary scan testusing the boundary scan elements shown in FIG. 4;

FIG. 8 is a schematic diagram showing an example of a boundary scan testusing the boundary scan elements shown in FIG. 4; and

FIG. 9 is a block diagram showing an example of a conventionalcommunication system to which boundary scan elements are applied.

BEST MODE FOR EMBODYING THE INVENTION Configuration of First Embodiment

FIG. 1 is a block diagram showing a first embodiment of thecommunication system of the present invention.

The communication system la shown in this figure includes a plurality ofboundary scan elements 4 a-4 c, monitoring camera units (terminal units)6 a-6 c connected with the respective boundary scan elements 4 a-4 cthrough latch circuits 5 a-5 c, a communication controller device 3 forcontrolling the monitoring camera units 6 a-6 c through the boundaryscan elements 4 a-4 c, a single analog communication line (datacommunication line) 10 through which picture signals of the monitoringcamera units 6 a-6 c are transmitted, and an analog signal processingunit 7 for receiving the picture signals transmitted from the analogcommunication line 10; furthermore, to the communication controllerdevice 3 is connected an operation switch device 2, and to the analogsignal processing unit 7 is connected a monitor device 8 for displayingthe picture signals output from the monitoring camera units 6 a-6 c.

The boundary scan elements 4 a-4 c have the same configuration as thatshown in FIG. 4, and are connected in series to the communicationcontroller device 3. Specifically, the output terminal 3 a of thecommunication controller device 3 is connected to the TDI terminal ofthe boundary scan element 4 c, the TDO terminal of the boundary scanelement 4 c is connected to the TDI terminal of the next boundary scanelement 4 b, and the TDO terminal of the boundary scan element 4 b issimilarly connected to the TDI terminal of the boundary scan element 4a. Finally, the TDO terminal of the boundary scan element 4 a isconnected to the input terminal 3 b of the communication controllerdevice 3. Accordingly, the data being supplied to the boundary scanelements 4 a-4 c or the data being output from the boundary scanelements 4 a-4 c are always transferred in the direction from theboundary scan elements 4 c to 4 a.

Further, the TCK terminal and the TMS terminal of each of the boundaryscan elements 4 a-4 c are supplied with a clock signal and a mode signalfrom the communication controller device 3, respectively, and therebythe respective boundary scan elements 4 a-4 c function synchronously.

The input terminals and output terminals (not shown) of the boundaryscan elements 4 a-4 c are connected with the corresponding latchcircuits 5 a-5 c, respectively. Control data set in the boundary cellsare output through the respective latch circuits 5 a-5 c to thecorresponding monitoring camera units 6 a-6 c, and the status data ofthe monitoring camera units 6 a-6 c, such as data indicating whether themonitoring operation is in action or not, data indicating the directionof monitoring, and data indicating the magnitude of the shooting lens,are input through the latch circuits 5 a-5 c to the boundary cells.

The monitoring camera units 6 a-6 c are arranged at positionscorresponding to objects to be monitored, carry out the shooting of theobjects to be monitored while switching the shooting directions and themagnitude of the shooting lens in accordance with the control dataoutput from the corresponding latch circuits 5 a-5 c, and transmit backto the corresponding latch circuits 5 a-5 c the shooting conditions andthe like as the status data. In addition, the monitoring camera units 6a-6 c directly transmit the picture signals obtained by the shooting tothe analog communication line 10 without the intermediary of the latchcircuits 5 a-5 c.

The communication controller device 3 includes hardware circuits,microprocessor circuits, and the like, and transmits control data to therespective boundary scan elements 4 a-4 c in accordance with selectionindication data output from the operation switch device 2, therebycontrolling the monitoring camera units 6 a-6 c. It also receives thestatus data from each of the boundary scan elements 4 a-4 c, andanalyzes the same to check whether or not the monitoring camera units 6a-6 c are functioning normally, and the like. Moreover, it controls theanalog signal processing unit 7 in accordance with the selectionindication data output from the operation switch device 2, so that thepicture signals transmitted from the analog communication line 10 aredisplayed on the monitor device 8.

The analog communication line 10 is composed of a coaxial cable and thelike, and connects between the analog signal input terminal of theanalog signal processing unit 7 and the analog signal output terminalsof the respective monitoring camera units 6 a-6 c in parallel. And, itfetches a picture signal output from any one of the monitoring cameraunits 6 a-6 c, and transmits the same to the analog signal inputterminal of the analog signal processing unit 7.

The analog signal processing unit 7 includes an analog signal inputcircuit for fetching a picture signal, an analog signal processingcircuit for applying designated image processing to the picture signalfetched by this analog signal input circuit, a picture signal outputcircuit for outputting the picture signal image processed by this analogsignal processing circuit in the form of an analog signal or in the formof a digital signal, and a control circuit for controlling thesecircuits in accordance with operation indication signals from thecommunication controller device 3, and the like.

In accordance with instructions output from the communication controllerdevice 3, this analog signal processing unit 7 fetches a picture signalsupplied through the analog communication line 10, and superimposesthereon a status determination result and the like of the respectivemonitoring camera units 6 a-6 c supplied from the communicationcontroller unit 3 before supplying the same to the monitor device 8 in adesignated signal form among the analog signal form or the digitalsignal form.

The operation switch device 2 has a plurality of push button switchesand the like, generates selection indication data and the like forselecting the monitoring camera units 6 a-6 c and the like in accordancewith the operation content of the respective push button switches, andsupplies the same to the aforesaid communication controller device 3. Auser can operate this operation switch device 2 to make thecommunication system la execute particular processing.

The monitor device 8 is constituted by a CRT unit, liquid crystaldisplay unit, or the like having a display capacity required to displaypictures of the objects to be monitored, and fetches the picture signalin the analog signal form or picture signal in the digital signal formoutput from the analog signal processing unit 7 to displays the pictureexpressed by this picture signal.

Operation of First Embodiment

Next, referring to the block diagram shown in FIG. 1, the operation ofthe communication system 1 a will be described in detail. Thecommunication system 1 a can be manually switched to display the pictureand the like of any monitoring camera unit 6 a-6 c desired, and can beautomatically switched to display the picture and the like of therespective monitoring camera units 6 a-6 c in rotation.

Manual Switching Operation of Monitoring Camera Units 6 a-6 c

When manual selection indication data are transmitted from the operationswitch device 2 to the communication controller device 3, thecommunication controller device 3 prepares control data required to turnon one of the monitoring camera units 6 a-6 c designated by the manualselection indication data and to turn off the other monitoring cameraunits 6 a-6 c. These control data are then transmitted through thecommunication lines 9 and set into the boundary cells on the outputsides of the respective boundary scan elements 4 a-4 c.

At the same time, from the communication control device 3 to the analogsignal processing unit 7 is output an operation indication signalindicating a fetch instruction for a picture signal, which makes theanalog signal processing unit 7 ready for the fetching operation ofpicture signals.

Next, when a mode signal indicating an output instruction for controldata is output from the TMS terminal 3 c of the communication controllerdevice 3, the control data set in the boundary cells on the output sidesof the respective boundary scan elements 4 a-4 c are output to thecorresponding latch circuits 5 a-5 c, and further transmitted to therespective monitoring camera units 6 a-6 c. According to the content ofthe control data received, each of the monitoring camera units 6 a-6 crecognizes whether signal output permission is issued or not, and onlyone of the monitoring camera units, e.g. the monitoring camera unit 6 c,transmits its picture signal onto the analog communication line 10. Thepicture signal transmitted is fetched into the analog signal processingunit 7, and, further, a picture according to that picture signal isdisplayed on the monitor device 8.

Subsequently, unless the operation switch device 2 is operated, themonitoring camera units 6 a-6 c hold their states; and when theremaining monitoring camera unit 6 a or 6 b is selected, manualselection indication data are newly prepared, and the picture of eithermonitoring camera unit 6 a-6 c selected is displayed on the monitor 8through the procedures described above.

Automatic Switching Operation of Monitoring Camera Units 6 a-6 c

When automatic selection indication data are transmitted from theoperation switch device 2 to the communication controller device 3, thecommunication controller device 3 prepares control data required to turnon one of the monitoring camera units 6 a-6 c and to turn off the othermonitoring camera units 6 a-6 c. This is followed by the same processingas that in the initiative switching operation described above, so thatthe picture of the monitoring camera unit selected, e.g. 6 a, isdisplayed on the monitor 8.

Then, after elapse of a certain time set in advance, the communicationcontroller device 3 prepares control data required to turn on themonitoring camera unit 6 b which follows the monitoring camera unit 6 aselected initially and to turn off the remaining monitoring camera units6 a and 6 c. These control data are transmitted through thecommunication lines 9, and the picture of the monitoring camera unit 6 bis displayed on the monitor 8 through the same processing as that in thecase described above.

Thereafter, the selecting operations for the respective monitoringcamera units 6 a-6 c described above are cyclically repeated at eachelapse of the certain time set in advance, so that the pictures obtainedby the respective monitoring camera units 6 a-6 c are sequentiallydisplayed on the monitor device 8.

Status Detecting Operation of Monitoring Camera Units 6 a-6 c

Here, in parallel to the manually-/automatically-switched picturefetching operation or the image display operation of the respectivemonitoring camera units 6 a-6 c described above, status data indicatingthe operation status and the like are output from the respectivemonitoring camera units 6 a-6 c. These status data are latched by thecorresponding latch circuits 5 a-5 c before transmitted to the inputterminals of the respective boundary scan elements 4 a-4 c and set intothe boundary cells.

Subsequently, when a TMS signal indicating a read instruction is outputfrom the TMS terminal 3 c of the communication controller device 3, thestatus data set in the boundary cells are serially transferred from theTDO terminals and supplied to the input terminal 3 b of thecommunication controller device 3.

The communication controller device 3 analyzes the status data received,and makes judgements as to the shooting conditions of the respectivemonitoring camera units 6 a-6 c, whether or not the respectivemonitoring camera units 6 a-6 c are functioning normally, whether or notthe communication lines 9 or the like are not broken, or the like. Theserespective detection results and respective judgement results can alsobe displayed on the monitor device 8 through the analog signalprocessing unit 7.

Effect of First Embodiment

As has been described above, in the first embodiment of the presentinvention, the picture signals transmitted from the monitoring cameraunits 6 a-6 c are directly transmitted to the analog signal processingunit 7 through the analog communication line 10 without the intermediaryof the boundary scan elements 4 a-4 c. This allows the high-ratetransfer and processing of picture signals without impairing the effectof the high-rate data transfer due to the use of the boundary scanelements 4 a-4 c. Moreover, the picture signals of the plurality ofmonitoring camera units 6 a-6 c can be transmitted by a single analogcommunication line 10, with the result of simple wiring; besides, thesynchronous functioning of the boundary scan elements 4 a-4 c avoids thetime rags and interference to the picture signals in switching themonitoring camera units 6 a-6 c.

Configuration of Second Embodiment

FIG. 2 is a block diagram showing a second embodiment of thecommunication system according to the present invention.

The difference between the communication system 1 b shown in this figureand the communication system la shown in FIG. 1 consists in thatspecially-designed boundary scan elements 11 a-11 c are used in place ofthe boundary scan elements having the constitution shown in FIG. 4; thiscauses the speed-up of the transfer of control data and the like. Otherconfigurations and functions are the same as those of the communicationsystem 1 a; and to the same parts are assigned the same numerals in FIG.2. Hereinafter, concrete description will be made on the boundary scanelements 11 a-11 c.

As shown in FIG. 3, each of the boundary scan elements 11 a-11 c isincorporated into a chip case 12 as a single package, and includes,similarly to the boundary scan element shown in FIG. 4, boundary cells19 and 20, a TAP controller 25 for controlling input and output of datato or from the boundary cells 19 and 20, a TDI terminal 14 for receivingserial data, a TDO terminal 15 for transmitting serial data, a TCKterminal 17 into which a clock signal is input, and a TMS terminal 16for receiving a mode signal for switching the operation mode of the TAPcontroller 25; and, if required, it is further provided with a bypassregister 21, an ID CODE register 22, an instruction register 23, and thelike (boundary scan resister 24).

In the boundary scan elements 11 a-11 c of FIG. 3, however, the boundarycells 19 and 20 are not connected all in series, and are divided intooutput cells (output-side boundary cells) 20 and input cells (input-sideboundary cells) 19 corresponding to the output terminals 18 and inputterminals 13 arranged on the exterior of the chip case 12, respectively.The input cells 19 and the output cells 20 are individually connected inseries, and are connected in parallel between the TDI terminal 14 andthe TDO terminal 15.

Then, as a special operation, the boundary scan elements 11 a-11 c havea mode in which either the input cells 19 or the output cells 20 aloneare brought into their operative states and the other are brought intotheir non-operative states.

Thereby, when the respective input cells 19 are put in their operativestates, the status data and the like fetched into the respective inputcells 19 through the respective input terminals 13 can be directlyoutput from the TDO terminal 15 without being shifted through the outputcells 20 as conventionally.

Moreover, when the respective output cells 20 are in their operativestates, the control data and the like input to the TDI terminal 14 canbe shifted and set directly into the respective output cells 20, andoutput from the respective output terminals 18 to the external, withoutbeing shifted through the input cells 19 as conventionally.

By the use of the operation mode inherent in the boundary scan elements11 a-11 c described above, the communication system 1 b composed of suchboundary scan elements 11 a-11 c is further improved in the datatransfer rate between the communication controller device 3 and therespective boundary scan elements 11 a-11 c as compared with thecommunication system la described above.

Other Embodiments

Further, while in the first and second embodiments described above, thepicture signals in the analog signal form are output from the respectivemonitoring camera units 6 a-6 c and they are input through the analogcommunication line 10 to the analog signal processing unit 7, picturesignals in the digital signal form may be output from the respectivemonitoring camera units 6 a-6 c and they may be input through a digitalcommunication line (or a bus, an optical fiber cable, or the like) to adigital signal processing unit.

In addition, while in the first and second embodiments described above,the monitoring camera units 6 a-6 c are controlled as the terminal unitsof the communication systems 1 a and 1 b, other terminal units e.g. ameasuring device for measuring physical values of the objects to bemonitored, individual computer unit in distributional arrangement, andthe like may be controlled to collect measurement, processing results,and the like output from these respective measuring devices andrespective computer unit.

What is claimed is:
 1. A communication system comprising: a plurality ofboundary scan elements including input and output terminals, a pluralityof boundary cells individually assigned to the respective inputterminals and output terminals, a TAP circuit for controlling input andoutput of data to or from said boundary cells, a TDI terminal forinputting serial data to be supplied to said boundary cells, a TDOterminal for outputting data from said boundary cells in a form ofserial data, a TCK terminal into which a clock signal is input, and aTMS terminal into which a mode signal for switching the operation modeof said TAP circuit is input; a plurality of data output units, eachbeing connected in parallel with each of said boundary scan elements orprovided with an IC into which each of the elements is incorporated; acommunication controller connected with said boundary scan elements inseries, said communication controller transmitting/receiving throughsaid boundary scan elements control data for individually controllingsaid data output units; a signal data communication line connected withsaid data output units in parallel; and a signal processing unitconnected with said signal data communication line and saidcommunication controller for transmitting output data from said dataoutput units under a control of said communication controller.
 2. Thecommunication system according to claim 1, wherein said output data areanalog signals; and said signal processor unit processes said analogsignals.
 3. The communication system according to claim 1, wherein saidboundary cells include a plurality of input-terminal-side boundary cellsconnected in series and assigned to said input terminals individually,and a plurality of output-terminal-side boundary cells connected inseries and assigned to said output terminals individually, and saidinput-terminal-side boundary cells and said output-terminal-sideboundary cells are connected in parallel between said TDI terminal andsaid TDO terminal.
 4. The communication system according to claim 1,wherein said data output units include monitoring cameras, measuringdevices for measuring physical values of objects, and computer unitsarranged separately.
 5. The communication system according to claim 4,further comprising latch circuits, each being situated between each ofthe data output unit and each of the boundary scan elements.